Defence Metallurgical Research Laboratory

About: Defence Metallurgical Research Laboratory is a facility organization based out in Hyderabad, India. It is known for research contribution in the topics: Microstructure & Alloy. The organization has 1208 authors who have published 2662 publications receiving 51663 citations.

Genotoxicity of nano- and micron-sized manganese oxide in rats after acute oral treatment.

Abstract: The use of nanotechnology has led to rapid growth in various areas. Manganese oxide (MnO2) nanomaterials (NMs) are typically used for biomedical applications. However, characterizing the potential human health effects of MnO2 NMs is required before fully exploiting these materials. The aim of this study was to investigate the acute oral toxicity of MnO2 NMs and MnO2-bulk particles in female albino Wistar rats. The genotoxic effects were examined using comet, micronucleus and chromosomal aberration assays. Nanosized MnO2 (45nm) significantly (p<0.01) increased DNA damage in peripheral blood leukocytes and micronuclei and enhanced chromosomal aberrations in the bone marrow cells at 1000mg/kg bw. These findings showed that the neurotoxicity of MnO2-45nm in the brain and red blood cells, as determined through acetylcholinesterase activity, was significantly (p<0.01) inhibited at 1000 and 500mg/kg bw doses. MnO2-45nm disrupted the physicochemical state and neurological system of the animals through alterations in ATPases via the total Na(+)-K(+), Mg(2+) and Ca(2+) levels in the brain P2 fraction. In addition, 500 and 1000mg/kg bw doses of MnO2-45nm caused significant changes in AST, ALT and LDH levels in the liver, kidney and serum of treated rats. Significant tissue distribution was found in all tissues in a dose- and time-dependent manner. MnO2-45nm exhibited much higher absorptivity and tissue distribution compared with MnO2-bulk. A large fraction of MnO2-45nm was cleared in the urine and feces. The histopathological analysis revealed that MnO2-45nm caused alterations in the liver, spleen and brain. These findings will provide fundamental information regarding the potential toxicities and biodistribution of nano and bulk MnO2 generated through acute oral treatment.

Identification of suitable process parameters for friction surfacing of mild steel with AA6063 aluminium alloy

Abstract: The present study is aimed at identifying suitable process parameters for friction surfacing of IS2062 mild steel with AA6063 aluminium alloy and obtain relationships between the input parameters and the process response that can be used for sound coating with adequate strength and ductility. Factorial experimental design technique was used to investigate and select the parameter combination to achieve adequate strength and ductility. Mechatrode rotational speed, axial load and substrate traverse speed were observed to be the most significant factors on the process response. Based on the results, it was observed that (i) lower axial load and traverse speed with high rotational speed and (ii) higher axial load and traverse speed with lower rotational speed produced sound coatings. It has also been observed that sound coatings could be obtained in a narrow set of parameter range as the substrate-coating materials are metallurgically incompatible and have propensity to form brittle intermetallics.

Improved magnetoelectricity by uniaxial magnetic field pressed and sintered composites in BaTiO3 (x)–BaFe12O19 (1 − x) system (x = 0.8, 0.6)

Abstract: A composite system BaTiO3 (x)–BaFe12O19 (1 − x) with ferroelectric BaTiO3 phase (BT) and a ferrimagnetic BaFe12O19 phase (BF), in which x varies from 0.8 to 0.6, have been prepared by solid state double sintering method. The presence of ferroelectric (BT) and ferrimagnetic phase (BF) have been confirmed from X-ray diffraction analysis, indicating the formation of composite system. Microstructure observation shows the distribution of BT and BF grains with respect to different compositions. With the variation of x in the composite system, a typical magnetic hysteresis loops have been observed at room temperature with high magnetization and coercivity values. The ferroelectric measurements have displayed hysteresis loops for x = 0.8 and 0.6 compositions. Magnetoelectric (ME) output have been recorded at room temperature for the both the compositions. The in situ magnetic field pressing at different magnetic fields followed by solid state sintering has enhanced the ME output value. Quadratic magnetoelectric signal is recorded indicating non-linearity in the system.

Environmental Pathway and Risk Assessment Studies of the Musi River's Heavy Metal Contamination—A Case Study

Abstract: The Musi River, in Hyderabad, the capital city of Andhra Pradesh state in India, is relatively dry for most of the year except for the four monsoon months when 700–800 mm of rain falls. Throughout the year, sewage, industrial, and hospital waste is released into the river. In the present work the Musi River from Amberpet Bridge to Nallacheruvu (8 km stretch) was assessed and monitored for heavy metal contamination attributable to sewage and industrial effluents. Twelve locations were assessed for Zn, Cr, Cu, Ni, Co, As, Hg, Cd, and Pb in soils, waters, forage grass, milk, and vegetables. A sequential extraction scheme revealed that high levels of Zn, Cr, and Cu were associated with labile fractions, making them more mobile and phytoavailable. Human risk was assessed in people exposed to pollution by analyzing metals concentrations in venous blood and urine. Results showed high amounts of Pb, Zn, Cr, and Ni compared to permissible limits, attributable to the consumption of contaminated food. Metal...

Grain refinement during high temperature tensile testing of prior cold worked and peak aged Cu–Ti alloys: Evidence of superplasticity

Abstract: The high temperature tensile properties of solution treated, cold worked and peak aged Cu–1.5 wt.%Ti and Cu–4.5 wt.%Ti alloys have been investigated in the temperature range from room temperature (RT) to 550 °C. Yield strength (YS) and tensile strength (TS) of Cu–1.5Ti alloy were found to be independent of test temperature up to 350 °C and decreased thereafter, up to 550 °C. In the case of Cu–4.5Ti alloy, behaviour similar to Cu–1.5Ti alloy was observed. The decrease in strengths beyond 350 °C is attributed to coarsening of β′ precipitate particles at 450 °C and precipitation of equilibrium phase β at 550 °C. TEM analysis of the alloys confirms the presence of metastable and coherent Cu 4 Ti β′ precipitate when tested at 450 °C and equilibrium precipitate Cu 3 Ti, β at the test temperature of 550 °C. It is interesting to note that in the cold worked and peak aged Cu–Ti alloys tested at elevated temperatures, ductility (% elongation) was found to increase with the test temperature up to 550 °C which is attributed to dynamic recrystallisation. The large elongation (160%) observed in Cu–4.5Ti alloy at the test temperature of 550 °C is an indication of superplasticity. We are reporting the discovery of superplasticity in Cu–4.5Ti alloy for the first time. Ductile mode of fracture was observed in these alloys tested at elevated temperatures, i.e. at 350 and 450 °C. High temperature tensile properties of Cu–Ti alloys are found to be superior to those of Cu–Be alloys (C17200 and C17510).